5 Questions about COVID-19 vaccine

with Dr. Jim Kellner

How did we get COVID-19 vaccines so quickly?

COVID-19 vaccine development has been rapid but not rushed, and the compression of the timeline from the typical 10-15 years for new vaccines to less than one year was accomplished though carefully conducting multiple steps of vaccine development simultaneously instead of sequentially.

The new technology used for some vaccines, notably the mRNA vaccines (i.e., Pfizer and Moderna), has been developed over the last 30 years. Once the SARS-CoV-2 virus genetic code was known in January 2020, the development of experimental vaccines took only a few days. Because the clinical trials were conducted in countries where there were a lot of cases of COVID-19 occurring, it did not take long for enough cases to occur to be able to look at the initial results to see if the vaccine was working.

Canada made advance purchase agreements for multiple possible vaccines, paying for doses to be produced and ready-to-use before it was known if the vaccines would work. Health Canada adopted a rolling approval process to consider information from the vaccine companies as it became available. All of this was facilitated by large numbers of scientists and drug companies pivoting their focus to COVID-19 and large amounts of public funding from governments and donors.

Does it matter which vaccine a person receives? Is there one that’s better than others?

The mRNA vaccines appear to have better numbers on the basis of preventing even mild infections, with Pifzer and Moderna each being more than 90 per cent effective in preventing these infections. However, all the approved vaccines in Canada have similar ability to prevent severe disease and death; over 80 per cent at least. Some of the other effects, like preventing asymptomatic transmission or benefit in very frail persons, remain unknown.

What can a person expect after receiving a COVID-19 vaccine?

Many people report a profound sense of wellbeing immediately after receiving their first dose of a COVID-19 vaccine!

It is normal and expected to have local or systemic effects for a few days after receiving the first or second vaccine dose and the effects may be more pronounced after the second dose. The most common effects (which occur in more than 10 per cent of people) include pain at the site of injection, perhaps with redness or swelling, as well as tiredness, headache, muscle and joint pain, fever, and chills.

The most important rare severe side effect after the mRNA vaccines is a severe allergic reaction (4 cases per million doses delivered). There is a current concern in Europe about whether the AstraZeneca vaccine is associated with the rare occurrence of blood clots or bleeding, but the issue is still being investigated. Overall, these are proving to be very safe and effective vaccines. 

Will these vaccines be good for life or will they be yearly like influenza?

This is not known, for two reasons. First, it is not clear how long the immune response will last. Some vaccines, such as measles, usually lead to a lifelong protective immune response. Others require regular booster doses throughout life, such as tetanus which must be boosted every 10 years. Second is how much the SARS-CoV-2 virus will mutate, requiring revaccination with new versions of the vaccine to protect against new strains. With the development of new variants occurring, it seems revaccination with new versions of the vaccines may be necessary periodically but not necessarily every year as with influenza vaccines.

Are there any risks if a person is vaccinated, but their household members or bubble mates aren’t?

Although the vaccines protect the recipient extremely (but not perfectly) well, and because we don’t yet know how well the vaccine protects against asymptomatic transmission, we don’t yet know how much risk there is for vaccinated and unvaccinated persons to be in close contact without masks. The vaccinated person will still be at some risk of getting sick, and they could also unintentionally (asymptomatically) pass the virus to an unvaccinated person. 

Dr. Jim Kellner is Professor in the Departments of Pediatrics; Microbiology, Microbiology, Immunology & Infectious Diseases; and Community Health Sciences at the Cumming School of Medicine at the University of Calgary and works with Alberta Health Services. Dr Kellner is also a member of the Leadership Group for Canada’s COVID-19 Immunity Task Force.

For more information, visit covid19immunitytaskforce.ca